Electric switch device



Nam 20, 1951 C. M. HINE'S ELECTRIC SWITCH DEVICE Filed March 29, 1949 JNVENTOR. CLAUDE M. HINES ATTORNEY Patented Nov. 20, 1951 ELECTRIC SWITCH-DEVICE Claude M.. Hines, Verona, Pa., assignor to Westinghouse Air Brake Company, acorpcration of Pennsylvania Application-March 29, 1949, Serial No. 84,036

3 .Claims.

This invention relates'to electric'switches and more particularly to a switch device adapted to minimize arcing due to circuit interruption.

Arcing at the contact elements (hereinafter referred to simply as contacts) of a circuit-interrupter or switch device incidental to circuit interruption has long been a problem, particularly in high voltage and high current circuitinterrupters. In the smaller switch devices the problem exists to alesserextent. In all cases, the service life of an interrupter or switch depends largely, if not entirely, upon the amount of pitting or burning of the separable contacts resulting from arcing.

It is an object of this invention to provide an improved electric switch device characterized by an arrangement for minimizing arcing at the separable contacts thereof upon circuit inte"- ruption and thus prolonging the service life of the device.

It is also an object of this invention topr-ovide an improved electric switch device that operates automatically to introduce resistance into the circuit to reduce the current in the circuit at the instant of circuit interruption.

Otherobjects and advantages of the invention will appear in the following more detailed de scription thereof, taken in connection with the accompanying dr'awingsin which Fig. 1 is a side view, partly in section, of an electrical switch device constructed in accordance with myinvention and shown in its closed position; Fig. 2 is a fragmentary sectional view, taken along the line 2-2 of Fig. 1, and showing further details of construction; and Fig. 3 is a side view, partly in section, showing the switch device in its open position;

Referring to Fig. 1 of the drawings, the switch device comprises a rigid current-carrying arm l, two flexibleresilient contact arms 2 and 3, of suitable metal or metallic alloy, inherently biased toward each other as more fully explained hereinafter; and a rigid stop arm 4 of insulating material positioned between said flexible contact arms 2 and 3, all ofithearms l, 2, 3 and 4 being suitably mounted in a basex5 of suitable insulating material.

Interposed between arms I and 2 and having itS'OPDOSltBi ends' suitably electrically connected,

as'by'solder'ing, to arms I and .2, respectively, is

av variable resistance spring transducer 6 which automatically stretchesresponsively to downward movement of contact'arml. It is a characteristioof the. transducer 6 that asmall amount of displacement: orextension-of: the; transducer; re f suits in a large increase of resistance of the transducer. The spring transducer 6 is so constructed that as. it is expanded or stretched from its normal contracted position the turns of the spring progressively separate, thereby eiiecting a. corresponding increase in the electrical resistance of the spring. The percentage change in resistance of the spring transducer 8 may be hundreds of times greater than the percentage change in length as it is expanded. Spring transducers of this type have been previously known and the transducer, in itself, is thus not my invention.

The ends of arms I and 3 mounted in the base 5 are provided with suitable terminals 1 and ,8 to enable the arms I and 3 to be connected to a circuit (not shown) which is to be interrupted.

The free" ends of the resilient contact arms 2 and 3 are provided with suitable contact discs 9 and ill which engage firmly in the normal or closed position of the switch due to the in herent bias of the two arms in opposite directions. In view of the fact that flexible arms 2 and 3 are thus inherently biased, it follows that if arm 3 is moved downwardly, as by means to be described hereinafter, the arm 2 will also move downwardly, the contact discs 9 and i9 remaining engaged until the downward movement of these two arms is sufficient to permit arm 2 to engage the stop arm 4, at which time any further downward movement of arm 3 will cause the contact discs 9 and ID to part from each other. It must be noted here that the inherent biasing force in arm 2 is suflicient to cause the spring transducer 6 to be expanded as the arm 2 flexes downwardly. If the force causing the downward movement of arm 3 is removed, the resilient nature and the inherent biasing forces of the two arms 2 and,3 will cause these arms to return to the position shown in Fig. 1 wherein contact discs 9 and I0 reengage.

Any suitable means may be provided for moving arm 3 downwardly to the circuit-open position shown in Fig. 3 and holding the arm in such position until it is desired to return it to its normal circuit-closing position. As shown, such means may comprise a lever mechanism mounted in the base 5 andincluding'a yoke l I of insulating material straddling the arm 3 and having a transverse cylindrical portion l2 which engages the contact arm 3. The free ends of the yoke ll are provided with non-circular holes, shown as square holes in the drawing, to receive and interlochwith a square section of. a pin. 1 3 which extends transversely through a portion of the base 5. As will be seen in Fig. 2, pin I3 has cylindrical portions at opposite ends thereof to enable rotation thereof in the base and is secured therein by a suitable means such as a cotter pin I9. A lever I4, having a square hole therein through which the square portion of pin I3 extends, is mounted between the free ends of the yoke I I in such a manner that angular movement of the lever I4 will, through the medium of pin I3, be transmitted to and result in a corresponding angular movement of the yoke II. It will thus be seen that as the lever I4 is shifted in a clockwise direction from the position in which it is shown in Fig. 1, yoke II shiftscorrespondingly in the same direction to effect downward flexing movement of the contact arm 3.

The end or lever I4 adjacent to pin I3 has at angularly related flats I5 and 6 with which cooperates a leaf spring I! that is attached as by several screws I8 to the base 5 for the purpose of holding the lever I4 positively in either one of two different positions corresponding to the circuit-closed position and the "circuitopen position respectively of the contact arms 2 and 3.

' The switch device in its normal or closed position is as shown in Fig. 1. As previously explained, the two flexible arms 2 and 3 are biased towards each other and will thus be positioned in a substantially symmetrical relation to the stop arm 4 as shown in Fig. l with the contact discs 9 and III in engagement with each other. With the arm 2 in this position, the transducer or spring 6 will be held in its contracted position thereby, as explained previously, offering a minimum electrical resistance to a current flowing in' a circuit from terminal 'I by Way of arm I, transducer 6, arm 2, contact disc 9, contact disc I0 and arm 3 to the terminal 8.

When the lever I4 is shifted in a clockwise direction from the rotation in which it is shown gagement with flat I5. The resilient nature and the inherent biasing forces of the arms 2 and 3 will thus be effective to return the said arms to their normal position symmetric with respect to arm 4 and cause the contact discs 9 and ill to reeng-age.

Having now described the invention what I claim as new and desire to secure by Letters Patent is: a

1. An electrical switch device comprising two flexible resilient contact members inherently biased in opposite directions into engagement with each other, means for flexing one of said contact members in opposition to the biasing force thereof whereby movement of the other of said contact members is efiected correspondingly in response to the inherent biasing force thereof,

in Fig. l, the yoke II moves correspondingly in a clockwise direction and the transverse portion I2 of said yoke II pulls the arm 3 downwardly. The downward movement of arm 3 and contact disc l0 permits the inherent biasing force of arm 2 to flex the arm 2 and contact disc '9 downwardly. The downward movement of arm 2 and contact disc 9 will automatically stretch or expand the spring transducer 6, thereby increasing the electrical resistance thereof in the circuit described in the previous paragraph and thus decreasing the current in the said circuit. As the clockwise movement of lever I4 causes further downward movement of arms 2 and 3, the electrical resistance of the spring transducer 6 increases correspondingly until the arm 2 engages the stop arm 4, at which time the current in the said circuit will have been reduced so greatly that the parting of the contact discs '9 and I0 (as will occur with further downward movement), will cause little or no arcing. If the lever I4 is moved in a clockwise direction past the line of juncture between flats I5 and IS, the spring I'I will snap lever l4 to its full circuit-open position and maintain it in that position, as shown inFig. 3, by engagement with flat l6.

To restore the switch to its circuit-closed position it is necessary only to move the lever I4 in a counter-clockwise direction past the line of juncture between flats I5 and I6, whereupon spring I! will snap" the lever I4 to its circuitclosed" position andmaintain it thereon by en-' J5 a rigid stop member engageable by the other of said contact members upon a certain amount of movement in response to the inherent biasing force thereof, separation of said contact members being effected as the said one contact member is flexed in opposition to the inherent biasing force thereof beyond the point at which the said other contact member engages said stop member, and variable resistance means operatively responsive to the flexing movement of said other contact member in its traverse to the point of engagement with the stop member for effecting an increase of resistance in the circuit through said switch device immediately prior to disengagement of the contact members.

2. An electrical switch device comprising two flexible resilient contact members, inherently biased in opposite directions into circuit closing contact with each other, a rigid stop member positioned between said contact members, means for flexing one of said contact members away from said stop member in opposition to the biasing force thereof, thereby causing movement of the other of said contact members toward the stop member to be effected in response to the inherent biasing force thereof, the ultimate extent of movement of said other'contact member being so limited by engagement with said-stop member as to effect separation of said contact members from each other as the said one contact member is flexed beyond the point at which said other contact member engages said stop member, a rigid current-carrying support member, and a variable resistance spring transducer connected between said rigid current-carrying support member and said other contact member effective to progressively increase the resistance in the circuit through said switch device as the said other contact member traverses from its normal circuit-closing contact position to engagement with said stop member. 1

3. An electrical switch device comprising a supporting base of insulating material, a pair of flexible resilient contact members each secured at one corresponding end in said bas in spaced relation and being inherently biasedin opposite directions to effect circuit-closing engagement of the free ends thereof, a stop member of insulating material interposed between said contact members, means supported by said base operative to engage and move one of said contact members in opposition to the inherent biasing force thereof and thereby cause correspondingmovement of the other of said contact members in response to the inherent biasing-force thereof, said stop member being so positioned as to be engaged by said other contact member following a certain amount of flexing 'inovement thereof consequent upon the operation of said operating means to flex said one contact member in opposition to the inherent biasing force thereof, separation of said contact member being efiected in response to flexing movement of said one contact member an amount greater than that required to effect engagement of said other contact member with said stop member, a rigid current-carrying member supported by said base, a variable resistance spring transducer having one end physically and electrically connected to said rigid currentcarrying member and having the other end physically and electrically connected to said other contact member, the inherent biasing force of said other contact member being such as to stretch said transducer from a contracted position to an expanded position an amount corresponding to the amount of movement of said other contact member in its traverse to the point of engagement with said stop member, said 20 REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 532,838 Thomson Jan. 22, 1895 636,989 Hewson Nov. 14, 1899 FOREIGN PATENTS Number Country Date 884,035 France Apr. 12, 1943 

